Of all the words a proud, ambitious man might use to describe himself, perhaps only Abraham Lincoln would choose strange. Yet there it is. In one of his earliest wisps of autobiography, Lincoln wrote that he was “a strange, friendless, uneducated, penniless boy” when he emerged from the backwoods in his early 20s to make his way in the world. Editors of Lincoln’s Collected Works found the word so perplexing that they added an r to transform him into a mere stranger. But the late David Herbert Donald, one of Lincoln’s most admired biographers, astutely recognized that the man meant what he said.

Strange can mean odd or quirky, and Lincoln was certainly that. His foes nicknamed him the Gorilla, which captures his long-armed, shambling animal strength. His hands and feet were enormous, and his brow was simian. Yet when he spoke, a high and reedy voice twanged forth incongruously. At one moment, he might be braying loudly over one of his own salty jokes, and at the next, lost in catatonic silence.

Strange can also mean unfamiliar, alien. This too is Lincoln, who never quite fit in. The youthful Lincoln was a rawboned genius on an uncomprehending frontier. As President, he was a self-taught rustic surrounded by the polished burghers of Eastern society. Magnetic, keenly sensitive, often able to understand others better than they understood themselves, Lincoln was nevertheless profoundly isolated. Perhaps the early deaths of his mother and sister steeped him in sorrow so thoroughly that he learned to prefer loneliness to intimacy. He “never had a confidant,” his law partner William Herndon wrote. “He was the most reticent and mostly secretive man that ever existed.”

Despite interviewing dozens of Lincoln’s associates in the months after his death, J.G. Holland, an early biographer, found himself stumped. “There are not two who agree in their estimate of him,” he wrote. One would say “he was a very ambitious man”; another would assert “that he was without a particle of ambition.” People said that “he was one of the saddest men that ever lived, and that he was one of the jolliest men that ever lived … that he was a man of indomitable will, and that he was a man almost without a will; that he was a tyrant, and that he was the softest-hearted, most brotherly man that ever lived.” The real Lincoln, Holland concluded, was the sum of his contradictions.

This shape-shifting quality has allowed writers and politicians of every stripe to claim or reject Lincoln. He has been extolled as the Great Emancipator and criticized as a racist, praised as the hero of free labor and denounced as a tool of industrialists. Lionized as a man of peace and lambasted as a warmonger, beloved for his “new birth of freedom” and berated for his offenses against civil liberties and small government. Today he is philosophical soulmate to Presidents from both ends of the spectrum: George W. Bush quoted him last year on the 10th anniversary of the 9/11 attacks, while Barack Obama name-checked him as recently as the first debate.

But his strange contradictions were essential to his political success. Though he once declared that he “was a party man and did not believe in any man who was not,” Lincoln was, in important ways, always a party of one. He had an unusual ability to look at things through the eyes of his critics as well as his friends. He was willing to turn the same cold gaze on himself, to appreciate the limits of his popularity, which he studied closely because popularity is the wellspring of power. Once, an angry critic of the confounding George McClellan demanded to know why Lincoln tolerated the Union general’s insubordinate behavior. Lincoln coolly replied that McClellan was “a majority general,” while he was but “a minority President.” That makes all the difference in a government of, by and for the people.

It is tempting in times of great political strife and division—like Lincoln’s and our own—to pine for leaders who transcend politics. But the success of the 16th President teaches that hard times are precisely when political dexterity is needed most. Politics is the machinery by which we meet tough challenges. Lincoln drilled this idea into his closest aides so thoroughly that they could channel his philosophy after he was gone. “Every war is begun, dominated and ended by political considerations,” explained John Nicolay and John Hay, Lincoln’s faithful secretaries. “War and politics, campaign and statecraft, are Siamese twins, inseparable and interdependent.”

Americans of Lincoln’s day certainly pined for something more than his seemingly small-minded attention to politics. In the midst of the greatest crisis the nation had ever faced, Lincoln spent dozens of hours each week painstakingly distributing the rapidly growing number of federal jobs at his disposal. “He seems to me to be fonder of … patronage, and personal questions, than of the weightier matters of empire,” complained the celebrated author and attorney Richard Henry Dana. In August 1862, as the failure of McClellan’s Peninsula Campaign was bringing the Union’s military fortunes to their darkest pass, Lincoln nevertheless devoted huge blocks of time to selecting tax collectors authorized by the first internal-revenue act.

Why? Because he realized that by giving plums to exactly the right members of the opposition Democrats, the right Irish immigrants, the right Methodists—even the friends of influential newspaper editors—he could bind them more tightly to his shaky Union coalition. Politics today is often a matter of energizing a President’s base, but for Lincoln, success was a matter of adding new supporters: if he could collect enough, the Union could be restored. As Secretary of the Navy Gideon Welles came to appreciate, time spent by Lincoln on favor seekers was every bit as important to the war effort as time spent poring over military maps: “Never under any Administration were greater care and deliberation required” in dispensing presidential favors, for Lincoln was shoring up “a demoralized government and a crumbling Union.” America’s next President will face a version of this challenge as he tries to build a coalition to tackle such divisive issues as debt, taxes and immigration.

Lincoln as political strategist is front and center in Steven Spielberg’s new film. He trades votes, dangles patronage, hedges principles and tiptoes on the brink of deceit. He pleads, cajoles and threatens. He seems always to be at least two moves ahead of everyone else on the Washington chessboard. And he has to be, because what he is attempting—the passage of a constitutional amendment to end slavery, over the determined opposition of Copperhead Democrats—is both difficult and critically important. Lincoln makes glorious the earthy art of grubbing for votes.

Well before that showdown in the waning days of the war, Lincoln relied on his political acumen to survive and even thrive through the most perilous year in American history, 1862. It was the year in which the Civil War became a cataclysm, the federal government became a colossus and the Confederacy came nearest to winning its independence. In 1862, Lincoln rang the death knell for slavery with his Emancipation Proclamation. He established himself firmly as Commander in Chief and held the North together while unimagined carnage in battles like Shiloh and Antietam forged the military leaders who would eventually win the war—men like Grant, Sherman, Sheridan and Farragut. Under a constant cloud of a possible military coup, he fended off uprisings in Congress and among members of his Cabinet. He signed the visionary bills that created the transcontinental railroad, the modern fiscal system, the homesteading movement and the nation’s land-grant universities.

“Never has there been a moment in history when so much was all compressed into a little time,” one U.S. Senator observed. And never since the founding of the country had so much depended on the political skills of one man. As Obama and Mitt Romney reach the final hours of their race for the heavy prize of leading a polarized America through its next four years of challenges, they—and we—could learn a lot from the Lincoln of 1862.

One lesson: it’s not about them. lincoln never confused his mission with himself. He had the hide of a rhinoceros and a rare ability to set the past aside when turning former enemies into allies. His favorite expression, according to Hay, was “I am in favor of short statutes of limitations in politics.” To Lincoln, a grudge was a waste of resources. If a person could be useful, it mattered little whether he was friend or foe.

There is no better example than his decision in January 1862 to entrust leadership of the War Department to Edwin Stanton, a prominent Pennsylvania attorney. Years earlier, Lincoln had been retained as one of several lawyers helping defend a manufacturer of reaping machines against the powerful McCormick Co. in a patent dispute. Stanton was the star of the defense team, and he went to great lengths to humiliate Lincoln when the case went to trial. Calling him “that damned long-armed ape,” Stanton refused to seat Lincoln at counsel’s table. All that was forgotten when Lincoln went looking for a man brazen and hard enough to perform the thankless task of bringing order to the vast Union war machine.

Lincoln also teaches the lesson of patience. Hardly a day passed in 1862 without an exasperated lecture from someone about the need to take bold steps against both slavery and McClellan, yet Lincoln resisted. He needed to move gradually, to persuade himself and moderate voters of the North that he had exhausted all incremental steps. Even after he decided that the general must be fired and the slaves freed, he waited for the right political moment. His secretaries described this excruciating period. He “grew sensitive and even irritable,” wrote Nicolay and Hay. “Could no one exercise patience but himself?” The long wait for a victory with which to frame his Emancipation Proclamation was perhaps the most delicate interval of his presidency. Lincoln “was compelled to keep up an appearance of indecision which only brought upon him a greater flood” of demands for an answer, his aides wrote. “During no part of his Administration were his acts and words so persistently misconstrued.”

Anyone who thinks the risk of a gaffe is something new in the lives of Presidents should listen to Lincoln. Newspapers were so eager to bend his language to their own agendas that he learned to ration his speeches in self-defense and thus mastered the art of the extremely short yet powerful address—like the one at Gettysburg. As he said to a clamoring crowd in Maryland in October 1862, “In my present position it is hardly proper for me to make speeches. Every word is so closely noted that it will not do to make trivial ones.”

This painful interim was necessary because Lincoln understood that even in times of extreme polarization, the moderate center is the path to presidential success. Was then and is now. He offered an arresting metaphor one summer day in 1862, when a delegation of prominent New England abolitionists admonished him to take a stronger stand against slavery. After a long pause, he surprised his visitors by asking if they recalled “that a few years ago Blondin walked across a tightrope stretched over the falls of Niagara.”

Of course they remembered. Lincoln was referring to well-publicized stunts by the tightrope walker Jean-François Gravelet, who went by the name the Great Blondin. In 1859, Gravelet made a series of crossings over the roaring water. He pushed a wheelbarrow, stopped to cook an omelette, even carried his manager on his back. Lincoln visited Niagara Falls in 1848, and it left an indelible impression. Now the image of a man making his way along a 3-in. rope above such sublime and terrifying force struck Lincoln as a perfect metaphor for his own balancing act.

One of the visitors later recalled the President’s words: “Suppose,” Lincoln said, “that all the material values in this great country of ours, from the Atlantic to the Pacific—its wealth, its prosperity, its achievements in the present and its hopes for the future—could all have been concentrated and given to Blondin to carry over that awful crossing.” Suppose “you had been standing upon the shore as he was going over, as he was carefully feeling his way along and balancing his pole with all his most delicate skill over the thundering cataract. Would you have shouted at him, ‘Blondin, a step to the right!’ ‘Blondin, a step to the left!’ or would you have stood there speechless and held your breath and prayed to the Almighty to guide and help him safely through the trial?”

That reference to the nation’s achievements and hopes points to a final lesson from that fiery year. Even as he felt his way along the tightrope, Lincoln always kept his eye—and the eyes of the public—on the shore beyond. Americans have always been a future-oriented people, and our most admired Presidents have been the ones who painted tomorrow in bright colors, no matter how grim the today. Franklin D. Roosevelt, John F. Kennedy, Ronald Reagan: all were heirs to Abraham Lincoln, who sat down late in 1862, after an election setback, with his armies stalled and his party on the verge of revolt, and penned a detailed description of a future of unrivaled prosperity and national influence—a future that came true.

“We shall nobly save, or meanly lose, the last, best hope on earth,” he wrote in his unforgettable conclusion to that message. Perhaps it is strange that anyone could sound such a trumpet at such a time and have a strife-torn people believe it. But if the descendants of those people were to give up on that vision a century and a half later, in their own hour of strife, well, that would be even stranger.

Adapted from Rise to Greatness: Abraham Lincoln and America’s Most Perilous Year, by David Von Drehle, published by Henry Holt